Factors influencing survival in pre-viable preterm premature rupture of membranes

An observational study of a consecutive case series of pre-viable PPROM (16-24 gestational weeks) was performed between 2001 and 2007 in a single tertiary centre to identify factors that predict neonatal survival.

Detailed obstetric, ultrasound and neonatal data were abstracted from clinical records. Univariate, multivariate and receiver operator curve (ROC) analyses were performed to identify predictors of neonatal survival to discharge.

A total of 143 cases of PPROM were identified. Survival to discharge was less with PPROM at 16-20 weeks than 20-24 weeks (17% versus 39%; p=0.042). GA at PPROM, latency, mode of delivery and electronic foetal monitoring (EFM) were all significant, independent, predictors of survival (p<0.05). Ultrasound assessed amniotic fluid index (AFI) was a poor predictor of survival (area under ROC=0.649, 95% CI=0.532-0.766). A multivariable predictive model, including GA at PPROM, latency, mode of delivery and EFM had an area under the ROC of 0.954 (95% CI=0.916-0.993, sensitivity 97%, specificity 89% and accuracy 92%).

Pre-viable PPROM has a poor prognosis, though modern neonatal management techniques may improve survival in late pre-viable PPROM. The predictive model generated from this consecutive case series of this rare condition provides valuable data for counselling patients with this condition.